Acid (Ex)

The digestive acid that covers an ooze dissolves metals and organic
material, but not stone. Each slam and constrict attack deals 1d6
additional acid damage. Armor or clothing worn by a creature grappled
by an ooze takes the same amount of acid damage unless the wearer
succeeds on a DC 20 Reflex saving throw. A wooden or metal weapon that
strikes an ooze takes 1d6 acid damage unless the weapon's wielder
succeeds on a DC 20 Reflex save. The ooze's touch deals 12 points of
acid damage per round to wooden or metal objects, but the ooze must
remain in contact with the material for 1 full round in order to deal
this damage. The save DCs are Constitution-based.

Transparent (Ex)

Due to its lack of vivid coloration, an ooze is difficult to discern from its surroundings in most environments. A DC 15 Perception
check is required to notice the ooze. Any creature that fails to
notice an ooze and walks into it automatically suffers damage as if
struck by the ooze's slam attack and is immediately subject to a grab
attempt by the ooze.

Communication (Ex)

Slinking their way through cold swamps
and bleary marshlands, or sometimes even dungeons and caverns, gray
oozes consume any organic materials they encounter. Despite its lack of
intelligence, the gray ooze is a most problematic creature due to its
transparency. While the ooze cannot easily climb walls or swim, its
habit of lurking in the thick mud that lines the banks of marsh pools
or lying in harmless-looking pools on dull-colored dungeon floors makes
it dangerously easy to overlook and step on.

Some sages
believe that the gray ooze is the result of a failed alchemical
experiment, while others postulate that the first gray oozes
spontaneously arose from a cesspit of magical detritus. Of course,
these theories that gray oozes are not living organisms, but rather the
alchemical result of an unfortunate mixture of rare caustic fluids and
magical waste, are derided by many who dwell in areas plagued by the
creatures but which do not have a long history of magical pollution.

The
gray ooze adapts readily and swiftly to changes in environments, the
simple structure of its primeval form and its method of using fission
to reproduce all but ensuring that such changes occur. Listed below are
two such variants that adventurers have encountered.

Id Ooze (CR 6): Perhaps the
strangest variant gray oozes are those that have developed a
rudimentary intelligence, including the ability to communicate
telepathically with other oozes, or even the ability to blast enemies
with pulses of raw mental power. Id oozes are advanced gray oozes with
an Intelligence score of 2 (and thus gain skill ranks and
feats—typically 4 ranks in Stealth, Improved Initiative, and Toughness), can communicate basic empathic information with other id oozes within 100 feet via telepathy, and can use lesser confusion at will as a spell-like ability (CL equals the id ooze's HD).